# include <stdio.h>
# include <string.h>
# include <malloc.h>
struct addkey
{
  int no;
  struct addkey *link;
};
void main()
{
  int key,n,i;
  static int j=0;
  char cn[40],sn[40];
  struct addkey *h,*u,*p;
  printf("please enter a line :\ncn=");
  gets(cn);
  printf("please input the key:\nkey=");
  scanf("%d",&key);
  n=strlen(cn);
  h=u=(struct addkey *)malloc(sizeof(struct addkey));
  h->no=1;
  for (i=2;i<=n;i++)
  {
     u->link=(struct addkey*)malloc(sizeof(struct addkey));
     u=u->link;
     u->no=i;	/*第I個表元置編號I*/
  }
  u->link=h;	/*末表元后繼首表元，形成環*/
  while(n)
  {
    for(i=1;i<key;i++)	/*掠過M－1個表元*/
       u=u->link;	
    p=u->link;		/*P指向第M個表元*/
    u->link=p->link;	/*第M個表元從環中脫鉤*/
    sn[p->no-1]=cn[j++];
    free(p);	/*釋放第M個表元占用的空間*/
    n--;
   }
   printf("\nThe line cn is:");
   puts(cn);
   printf("\nThe line sn is:");
   puts(sn);
   printf("\n");

}